On the causes of declining Colorado River streamflows

by

Mu Xiao, Bradley Udall, Dennis P. Lettenmaier

,

Water Resources Research

States that over the period 1916-2014, the Upper Colorado River Basin (UCRB) naturalized streamflow declined by 16.5%, despite the fact that annual precipitation in the UCRB over that period increased slightly

Performs a set of experiments with the Variable Infiltration Capacity (VIC) hydrology model to examine the causes of the runoff declines

Results show that:

The pervasive warming has reduced snowpacks and enhanced evapotranspiration (ET) over the last 100 years

Over half of the long‐term decreasing runoff trend is associated with the general warming

Finds that:

Whereas a mid-century drought was caused primarily by pervasive low precipitation anomalies across UCRB, higher temperatures have played a large role in the ongoing post‐Millennium Drought

The post‐Millennium Drought has also been exacerbated by negative precipitation anomalies in several of the most productive headwater basins